U.S. patent number 10,823,670 [Application Number 16/343,439] was granted by the patent office on 2020-11-03 for compact ultraviolet light adsorption sensing system.
This patent grant is currently assigned to HONEYWELL INTERNATIONAL INC.. The grantee listed for this patent is HONEYWELL INTERNATIONAL INC.. Invention is credited to Yubin Lv, Bo Ren, Junfeng Wang, Li Wang.
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United States Patent |
10,823,670 |
Ren , et al. |
November 3, 2020 |
Compact ultraviolet light adsorption sensing system
Abstract
An ultraviolet (UV) light absorption sensing system (100)
includes a UV light source (110) configured to provide a UV sample
beam (115) of light toward a still or flowing fluid sample (117)
along a central axis (118) of a test cell (120), wherein the
central axis (118) is substantially orthogonal to a direction of
fluid flow. A reference light source (130) is configured to provide
a reference beam (133) along the central axis (118) of the test
cell (120). A first detector (140) is positioned to detect a first
portion (128) of the UV sample beam (115) and a first portion (138)
of the reference beam (133) that traverse the test cell (120). A
second detector (142) is positioned to detect a second portion
(146) of the UV sample beam (115) and a second portion (148) of the
reference beam (133) directly from the UV light source (110) and
reference light source (130).
Inventors: |
Ren; Bo (Morris Plains, NJ),
Lv; Yubin (Morris Plains, NJ), Wang; Junfeng (Morris
Plains, NJ), Wang; Li (Morris Plains, NJ) |
Applicant: |
Name |
City |
State |
Country |
Type |
HONEYWELL INTERNATIONAL INC. |
Morris Plains |
NJ |
US |
|
|
Assignee: |
HONEYWELL INTERNATIONAL INC.
(Morris Plains, NJ)
|
Family
ID: |
1000005156897 |
Appl.
No.: |
16/343,439 |
Filed: |
October 21, 2016 |
PCT
Filed: |
October 21, 2016 |
PCT No.: |
PCT/CN2016/102871 |
371(c)(1),(2),(4) Date: |
April 19, 2019 |
PCT
Pub. No.: |
WO2018/072201 |
PCT
Pub. Date: |
April 26, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190277751 A1 |
Sep 12, 2019 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N
21/05 (20130101); G01N 21/64 (20130101); G01N
30/74 (20130101); G01N 21/33 (20130101) |
Current International
Class: |
G01N
21/33 (20060101); G01N 21/64 (20060101); G01N
21/05 (20060101); G01N 30/74 (20060101) |
Field of
Search: |
;356/436-437 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
1225449 |
|
Aug 1999 |
|
CN |
|
104297190 |
|
Jan 2005 |
|
CN |
|
1580739 |
|
Feb 2005 |
|
CN |
|
1683921 |
|
Oct 2005 |
|
CN |
|
2637978 |
|
Apr 1990 |
|
FR |
|
0412250 |
|
Jan 1992 |
|
JP |
|
Other References
International Search Report and Written Opinion for Application No.
PCT/CN2016/102871, dated Jul. 20, 2017, 8 pages. cited by
applicant.
|
Primary Examiner: Akanbi; Isiaka O
Attorney, Agent or Firm: Alston & Bird LLP
Claims
The invention claimed is:
1. An ultraviolet (UV) light absorption sensing system comprising:
a UV light source configured to provide a UV sample beam of light
toward a still or flowing fluid sample along a central axis of a
test cell, wherein the central axis is substantially orthogonal to
a direction of fluid flow; a reference light source configured to
provide a reference beam along the central axis of the test cell; a
first detector positioned to detect a first portion of the UV
sample beam and a first portion of the reference beam that traverse
the test cell; and a second detector positioned to detect a second
portion of the UV sample beam and a second portion of the reference
beam directly from the UV light source and reference light
source.
2. The system of claim 1 and further comprising: multiple optical
components positioned with respect to the UV light source and
reference light source to control the UV sample beam and reference
beam such the UV sample beam and reference beam are nearly parallel
and close to each other.
3. The system of claim 2 wherein the multiple optical components
for each of the UV light source UV sample beam and reference beam
comprise: an opening to define a beam spread for each beam; and a
lens to focus the beams toward both the first detector and the
second detector.
4. The system of claim 2 wherein the multiple optical components
for the UV light source comprises a filter having a full width at
half maximum (FWHM) of transmittance spectrum of approximately 10
to 20 nanometers.
5. The system of claim 1 and further comprising a controller
coupled to the first and second detectors, wherein the controller
is configured to receive the measurements from the first and second
detectors and calculate UV absorption by the fluid sample.
6. The system of claim 1 wherein the UV light source has a
wavelength of approximately 254 nm and the reference light source
has a dominant wavelength selected to have no or little absorption
by the sample.
7. The system of claim 1 wherein the first and second detectors are
positioned relative to each other such that they receive
essentially an entire area of the UV sample beam and reference
beam.
8. An ultraviolet (UV) light absorption measurement system
comprising: a UV light source configured to provide a UV sample
beam of light toward a still or flowing fluid sample along a
central axis of a test cell, wherein the central axis is orthogonal
to a direction of fluid flow; an opening to restrict a beam width
of the UV sample beam; a first lens positioned between the test
cell and the UV light source to direct a portion of the UV sample
beam of light toward the test cell; a reference light source
configured to provide a reference beam substantially parallel to
and close to the UV sample beam; an opening to restrict a beam
width of the reference beam; a second lens positioned between the
test cell and the reference light source to direct a portion of the
reference beam of light toward the test cell; a first detector
positioned to detect the UV sample beam and reference beam that
traverse the test cell; a second detector positioned to detect the
UV sample beam and reference beam directly from the UV light source
and reference light source; a third lens positioned to receive a
portion of the UV sample beam and direct it toward the second
detector; and a fourth lens positioned to receive a portion of the
reference sample beam and direct the portion of the reference
sample beam toward the second detector.
9. The system of claim 8 and further comprising a controller
coupled to the first and second detectors, wherein the controller
is configured to receive the measurements from the first and second
detectors and calculate UV absorption by the fluid sample.
10. A method comprising: generating a UV sample beam via a UV light
source having a central axis of light extending toward a still or
flowing fluid sample along a central axis of a test cell, wherein
the central axis is substantially orthogonal to a direction of
fluid flow; generating a reference beam via a reference light
source having a central axis of light extending along the central
axis of the test cell; detecting via a first detector, a first
portion of the UV sample beam and reference beam that traverse the
test cell; and detecting via a second detector, a second portion of
the UV sample beam and reference beam directly from the UV light
source and reference light source, wherein the first and second
portions of the UV sample beam and reference beam are substantially
parallel from their sources to the first and second detectors.
Description
BACKGROUND
Measurement of water quality in real time may be performed by
measuring ultraviolet (UV) absorption of flowing liquid samples.
Disadvantages of current measurement systems include their large
size and high cost due to the use of one or more beam
splitters.
Typical UV measurement systems utilize a UV source and a separate
referent light source, and utilize optics, including at least one
beam splitter with coating film to re-direct light from both
sources through a fluid sample. A detector is used to measure the
light from both sources and an algorithm uses the measurements to
calculate UV absorption of the fluid sample.
SUMMARY
An ultraviolet (UV) light absorption sensing system includes a UV
light source configured to provide a UV sample beam of light toward
a still or flowing fluid sample along a central axis of a test
cell, wherein the central axis is substantially orthogonal to a
direction of fluid flow. A reference light source is configured to
provide a reference beam along the central axis of the test cell. A
first detector is positioned to detect a first portion of the UV
sample beam and a first portion of the reference beam that traverse
the test cell. A second detector is positioned to detect a second
portion of the UV sample beam and a second portion of the reference
beam directly from the UV light source and reference light
source.
An ultraviolet (UV) light absorption measurement system includes a
UV light source configured to provide a UV sample beam of light
toward a still or flowing fluid sample along a central axis of a
test cell, wherein the central axis is orthogonal to a direction of
fluid flow. An opening is positioned to restrict a beam width of
the UV sample beam. A first lens is positioned between the test
cell and the UV light source to direct a portion of the UV sample
beam of light toward the test cell. A reference light source is
configured to provide a reference beam substantially parallel to
and close to the UV sample beam. An opening is positioned to
restrict a beam width of the reference beam. A second lens is
positioned between the test cell and the reference light source to
direct a portion of the reference beam of light toward the test
cell. A first detector is positioned to detect the UV sample beam
and reference beam that traverse the test cell. A second detector
is positioned to detect the UV sample beam and reference beam
directly from the UV light source and reference light source. A
third lens is positioned to receive a portion of the UV sample beam
and direct it toward the second detector. A fourth lens is
positioned to receive a portion of the reference sample beam and
direct the portion of the reference sample beam toward the second
detector.
A method includes generating a UV sample beam via a UV light source
having a central axis of light extending toward a still or flowing
fluid sample along a central axis of a test cell, wherein the
central axis is substantially orthogonal to a direction of fluid
flow, generating a reference beam via a reference light source
having a central axis of light extending along the central axis of
the test cell, detecting via a first detector, a first portion of
the UV sample beam and reference beam that traverse the test cell,
and detecting via a second detector, a second portion of the UV
sample beam and reference beam directly from the UV light source
and reference light source, wherein the first and second portions
of the UV sample beam and reference beam are substantially parallel
from their sources to the first and second detectors.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of system for sensing UV absorption
through a fluid in a test cell according to an example
embodiment.
FIG. 2 is a block diagram illustrating the system of FIG. 1 coupled
to a pipe having fluid flowing there through according to an
example embodiment.
FIG. 3 is a flowchart illustrating UV sensing of a fluid sample
according to an example embodiment.
FIG. 4 is a block diagram illustrating electronics for controlling
light sources, detectors, and calculating UV absorption of a fluid
sample according to an example embodiment.
DETAILED DESCRIPTION
In the following description, reference is made to the accompanying
drawings that form a part hereof, and in which is shown by way of
illustration specific embodiments which may be practiced. These
embodiments are described in sufficient detail to enable those
skilled in the art to practice the invention, and it is to be
understood that other embodiments may be utilized and that
structural, logical and electrical changes may be made without
departing from the scope of the present invention. The following
description of example embodiments is, therefore, not to be taken
in a limited sense, and the scope of the present invention is
defined by the appended claims.
The functions or algorithms described herein may be implemented in
software in one embodiment. The software may consist of computer
executable instructions stored on computer readable media or
computer readable storage device such as one or more non-transitory
memories or other type of hardware based storage devices, either
local or networked. Further, such functions correspond to modules,
which may be software, hardware, firmware or any combination
thereof. Multiple functions may be performed in one or more modules
as desired, and the embodiments described are merely examples. The
software may be executed on a digital signal processor, ASIC,
microprocessor, or other type of processor operating on a computer
system, such as a personal computer, server or other computer
system, turning such computer system into a specifically programmed
machine.
In various embodiments, a real-time online solution for UV
absorption measurement of static or flowing liquid samples is
provided by a UV absorption measurement system 100 having a compact
and efficient optical structure as illustrated in FIG. 1. The
optical structure allows a significantly smaller measurement
optical structure and can greatly reduce the cost of such a
structure by eliminating expensive beam splitters.
The ultraviolet (UV) light absorption measurement system 100
includes a UV light source 110, such as a low pressure mercury
lamp, or other UV light producing source, configured to provide a
UV sample beam 115 of light toward a still or flowing fluid sample
117 along a central axis 118 of a test cell 120, wherein the
central axis 118 is orthogonal to a direction of fluid flow and
substantially centered through the test cell to ensure a portion of
the sample beam passes through a significant amount of the fluid
flow. If the test cell is cylindrical in shape, the central axis
corresponds to a diameter of the cylindrical test cell.
A shading box 123 is formed around the UV light source 110 in one
embodiment with an opening 125 positioned to create the UV sample
beam 115 with a desired beam width and direction. The opening 125
may comprise a hole or slit positioned to restrict generated UV
light to obtain a beam of desired width. A first lens 127 may be
positioned between the test cell 120 and the UV light source 110 to
receive and direct a portion 128 of the UV sample beam 115 toward
the test cell 120. A reference light source 130 is configured to
provide a reference beam 133 substantially parallel to and close to
the UV sample beam 115. An opening 135, such as slit or hole, is
positioned to restrict the generated light into a beam and provide
a desired beam width and direction of the reference beam 133. A
second lens 137 is positioned between the test cell 120 and the
reference light source 130 to receive and direct a portion 138 of
the reference beam 133 toward the test cell 120. Note that the
lenses may be single lenses or a battery of lenses in various
embodiments.
A first detector 140 is positioned to detect the portions of the UV
sample beam 115 and reference beam 133 that traverse the test cell
120. A second detector 142 is positioned to detect a portion of
each of the UV sample beam and reference beam directly from the UV
light source 110 and reference light source 130. A third lens 145
is positioned to receive a portion 146 of the UV sample beam 115
and direct the portion 146 toward the second detector 142. A fourth
lens 147 is positioned to receive a portion 148 of the reference
sample beam 133 and direct the portion 148 of the reference sample
beam 133 toward the second detector 142.
In one embodiment, the UV light source has a wavelength of
approximately 254 nm and the reference light source has a dominant
wavelength different than the UV source wavelength and selected to
have no or little absorption by the sample. Example reference light
sources may include an incandescent lamp or light emitting diode
(LED) or other light source capable of producing light having
wavelengths greater than approximately 390 nm yet still capable of
being detected by the detectors.
A filter 150 may be positioned in a path of the UV sample beam 115
between the UV source 110 and the test cell 120. The filter may be
positioned proximate the opening 125 to ensure the entire beam
width of the sample beam 115 is filtered, or at least the amount of
the beam that will be detected by the first and second detectors.
The filter in one embodiment has a dominant wavelength consistent
with the UV source of 254 nm, and may have a full width at half
maximum (FWHM) of transmittance spectrum of approximately 10 to 20
nanometers. The filter 150 may be used to avoid influence of other
wavelengths on measurements.
The test cell and lenses should allow transmittance of UV rays of
254 nm, and may be constructed of materials such as, for example,
quartz glass, UV ray transmitting glass or polymer, borosilicate
glass, sapphire, MgF.sub.2, LiF, and others. Quartz glass is
commonly used for UV applications. The lenses may each have an
optical axis that is positioned substantially parallel to the
central axis 118 of the test cell. The openings 125 and 135 may be
positioned close to each respective optical axis.
The light sources and detectors are effectively aligned
substantially in parallel such that the optical beams are nearly
parallel and close to each other, almost sharing a same beam area.
The placement of the light sources and optical components helps to
create light beams incident into the flowing liquid close to
vertical. In some embodiments, the light beams are as close to
vertical as possible for optimal sensing. The placement helps keep
the stability and invariability of the optical distance in the
liquid (at low concentration, the absorption is proportional to the
optical distance), and further may help to reduce the loss of the
light. The optical beams are straight and have no deflection
through large angles, such as is likely to result from the use of
beam splitters, which need not be used in example embodiments.
While the beams almost share a same beam area as a result of their
alignment, they should share enough area to facilitate calibration
and adequate measurement on the detectors such that the UV
absorption can be calculated within a desired accuracy.
In some embodiments, the detectors may have areas that are greater
than the beam size on the detectors to ensure an entire beam area
is detectable. The first and second detectors may comprise
UV-enhanced silicon photoelectric cells responsive at 254 nm and
dominant wavelength of the reference light source.
A controller 155 may be coupled to the first and second detectors
to receive signals representative of measured light from the
detectors. The controller 155 may include analog to digital
converters if the detector signals are analog in nature to convert
the detector signals to digital. The controller may be configured
to use the signals representative of measurements from the first
and second detectors and calculate UV absorption by the fluid
sample. The controller may be further configured to turn the light
sources on and off at different times such that the beams do not
interfere with each other. The controller is thus configured to
temporally alternate provision of the beams such that the detectors
only detect one type of light at any given time. A power supply 160
may be included to provide power to components of the system 100.
Note that not all connections to the power supply 160 are
illustrated to reduce the complexity of representation of the
system 100, but would be readily apparent to one of average skill
in the art. Power supply 160 may include a ballasting element for
the UV source 110, which may include a UV lamp. The ballasting
element operates to limit current for the UV lamp, as a resistance
of the lamp may decrease with increasing UV light generation.
The following paragraphs describe operation of the UV absorption
measuring system 100.
The portions of the beams that are directed toward the two
detectors may be characterized as ratios, ratio R.sub.a for UV lamp
and ratio R.sub.b for light source 2 (the subscript "a" corresponds
to the UV lamp, and the subscript "b" corresponds to light source 2
throughout the description). Before the system leaves factory, the
whole system may be calibrated with a blank sample. Assuming the
measured light intensity of UV lamp on detector 1 and detector 2
are I.sub.a1 and I.sub.a2, respectively. The measured light
intensity of light source 2 on detector 1 and detector 2 are
I.sub.b1 and I.sub.b2, respectively. The ratio R.sub.a is defined
by R.sub.a=I.sub.a1/I.sub.a2, and R.sub.b is given by:
R.sub.b=I.sub.b1/I.sub.b2. Then the calibrated ratio R.sub.a and
R.sub.b are saved in the system.
When a customer uses the system, the UV lamp and light source 2
will be turned on at different times. The customer sample would be
input in the flow cell. The measured light intensity on detector 1
and detector 2 are I.sub.a1'' and I.sub.a2'' for the UV lamp beam,
and I.sub.b1'' and I.sub.b2'' for light source 2, respectively.
To better understand the calibration process, a new parameter
I.sub.a1'' is used to represent the light intensity on detector 1
for UV lamp, when the flow cell is injected with blank sample and
the surfaces of the flow cell are the same as the one at
customer.
Then the transmittance of customer sample is given by:
.times..times.''.times..times.' ##EQU00001##
Thereof
.times..times.'.times..times..times.''.times..times.''.times..times..time-
s.'' ##EQU00002##
The function expression of f is determined in advance before the
system leaves the factory.
The absorption of a customer sample is calculated as follows:
Abs=-log.sub.10 (T).
FIG. 2 is a block diagram illustrating use of system 100 to measure
a flowing sample from a pipe 200. A first tap 210 is coupled to the
pipe 200 at an upstream location. A second tap 220 is coupled to
the pipe 200 at a downstream location. The first and second taps
are coupled across the test cell 120 and provide a sample of
flowing fluid from the fluid flowing through the pipe 200 in a
direction indicated by arrow 230. One or more pumps may be used to
obtain a desired flow rate in some embodiments.
FIG. 3 is a flowchart illustrating a method 300. Method 300
includes generating at 310 a UV sample beam via a UV light source.
The sample beam has an axis that is along a central axis of a test
cell having flowing fluid, wherein the central axis is
substantially orthogonal to a direction of fluid flow. At 320, a
reference beam is generated via a reference light source along the
central axis of the test cell. At 330, the method 300 includes
detecting via a first detector, a first portion of the UV sample
beam and reference beam that traverse the test cell. Method 300
further includes detecting at 340 via a second detector, a second
portion of the UV sample beam and reference beam directly from the
UV light source and reference light source, wherein the first and
second portions of the UV sample beam and reference beam are
substantially parallel from their sources to the first and second
detectors. Since no beam splitters are used in one embodiment, the
beams travel directly from their respective sources without being
deflected other than by the openings and lenses. At 350, UV
absorption of the fluid sample is calculated based on the detecting
by the first and second detectors.
In one embodiment, generating the UV sample beam and the reference
beam comprises temporally spacing the respective beams such that
each beam is detected separately. The UV sample beam may be
generated at a wavelength of approximately 254 nm and the reference
beam may be generated with a dominant wavelength selected to have
no or little absorption by the sample.
FIG. 4 is a block schematic diagram of a computer system 400 to
execute programming to control the light sources and calculate the
absorption of samples according to example embodiments. All
components need not be used in various embodiments. One example
computing device in the form of a computer 400, may include a
processing unit 402, memory 403, removable storage 410, and
non-removable storage 412. Although the example computing device is
illustrated and described as computer 400, the computing device may
be in different forms in different embodiments. For example, the
computing device may instead be a smartphone, a tablet, smartwatch,
or other computing device including the same or similar elements as
illustrated and described with regard to FIG. 4. Devices such as
smartphones, tablets, and smartwatches are generally collectively
referred to as mobile devices. Further, although the various data
storage elements are illustrated as part of the computer 400, the
storage may also or alternatively include cloud-based storage
accessible via a network, such as the Internet.
Memory 403 may include volatile memory 414 and non-volatile memory
408. Computer 400 may include--or have access to a computing
environment that includes--a variety of computer-readable media,
such as volatile memory 414 and non-volatile memory 408, removable
storage 410 and non-removable storage 412. Computer storage
includes random access memory (RAM), read only memory (ROM),
erasable programmable read-only memory (EPROM) & electrically
erasable programmable read-only memory (EEPROM), flash memory or
other memory technologies, compact disc read-only memory (CD ROM),
Digital Versatile Disks (DVD) or other optical disk storage,
magnetic cassettes, magnetic tape, magnetic disk storage or other
magnetic storage devices capable of storing computer-readable
instructions for execution to perform functions described
herein.
Computer 400 may include or have access to a computing environment
that includes input 406, output 404, and a communication interface
416. Output 404 may include a display device, such as a
touchscreen, that also may serve as an input device. The input 406
may include one or more of a touchscreen, touchpad, mouse,
keyboard, camera, one or more device-specific buttons, one or more
sensors integrated within or coupled via wired or wireless data
connections to the computer 400, and other input devices. The
computer may operate in a networked environment using the
communication interface 416 to connect to one or more remote
computers, such as database servers, including cloud based servers
and storage. The remote computer may include a personal computer
(PC), server, router, network PC, a peer device or other common
network node, or the like. The communication interface 416 may
include a Local Area Network (LAN), a Wide Area Network (WAN),
cellular, WiFi, Bluetooth, or other networks.
Computer-readable instructions stored on a computer-readable
storage device are executable by the processing unit 402 of the
computer 400. A hard drive, CD-ROM, and RAM are some examples of
articles including a non-transitory computer-readable medium such
as a storage device. The terms computer-readable medium and storage
device do not include carrier waves. For example, a computer
program 418 may be used to cause processing unit 402 to perform one
or more methods or algorithms described herein.
Examples
1. In example 1, an ultraviolet (UV) light absorption sensing
system includes a UV light source configured to provide a UV sample
beam of light toward a still or flowing fluid sample along a
central axis of a test cell, wherein the central axis is
substantially orthogonal to a direction of fluid flow. A reference
light source is configured to provide a reference beam along the
central axis of the test cell. A first detector is positioned to
detect a first portion of the UV sample beam and a first portion of
the reference beam that traverse the test cell. A second detector
is positioned to detect a second portion of the UV sample beam and
a second portion of the reference beam directly from the UV light
source and reference light source. 2. The system of example 1 and
further including multiple optical components positioned with
respect to the UV light source and reference light source to
control the UV sample beam and reference beam such the UV sample
beam and reference beam are nearly parallel and close to each
other. 3. The system of example 2 wherein the multiple optical
components for each of the UV light source UV sample beam and
reference beam includes an opening to define a beam spread for each
beam and a lens to focus the beams toward both the first detector
and the second detector. 4. The system of any of examples 2-3
wherein the multiple optical components for the UV light source
comprises a filter. 5. The system of example 4 wherein the filter
has a full width at half maximum (FWHM) of transmittance spectrum
of approximately 10 to 20 nanometers. 6. The system of any of
examples 1-5 and further comprising a controller coupled to the
first and second detectors, wherein the controller is configured to
receive the measurements from the first and second detectors and
calculate UV absorption by the fluid sample. 7. The system of
example 6 wherein the controller is further configured to
temporally alternate provision of the beams. 8. The system of any
of examples 6-7 wherein the UV light source has a wavelength of
approximately 254 nm and the reference light source has a dominant
wavelength selected to have no or little absorption by the sample.
9. The system of example 8 wherein the first and second detectors
comprise a UV-enhanced silicon photoelectric cell responsive at 254
nm and dominant wavelength of the reference light source. 10. The
system of any of examples 1-9 wherein the first and second
detectors are positioned relative to each other such that they
receive essentially an entire area of the UV sample beam and
reference beam. 11. In example 11, an ultraviolet (UV) light
absorption measurement system includes a UV light source configured
to provide a UV sample beam of light toward a still or flowing
fluid sample along a central axis of a test cell, wherein the
central axis is orthogonal to a direction of fluid flow. An opening
is positioned to restrict a beam width of the UV sample beam. A
first lens is positioned between the test cell and the UV light
source to direct a portion of the UV sample beam of light toward
the test cell. A reference light source is configured to provide a
reference beam substantially parallel to and close to the UV sample
beam. An opening is positioned to restrict a beam width of the
reference beam. A second lens is positioned between the test cell
and the reference light source to direct a portion of the reference
beam of light toward the test cell. A first detector is positioned
to detect the UV sample beam and reference beam that traverse the
test cell. A second detector is positioned to detect the UV sample
beam and reference beam directly from the UV light source and
reference light source. A third lens is positioned to receive a
portion of the UV sample beam and direct it toward the second
detector. A fourth lens is positioned to receive a portion of the
reference sample beam and direct the portion of the reference
sample beam toward the second detector. 12. The system of example
11 and further comprising a filter positioned in a path of the UV
sample beam between the UV source and the test cell. 13. The system
of example 12 wherein the filter has a full width at half maximum
(FWHM) of transmittance spectrum of approximately 10 to 20
nanometers. 14. The system of any of examples 11-13 and further
comprising a controller coupled to the first and second detectors,
wherein the controller is configured to receive the measurements
from the first and second detectors and calculate UV absorption by
the fluid sample. 15. The system of example 14 wherein the
controller is further configured to temporally alternate provision
of the beams. 16. The system of any of examples 11-15 wherein the
UV light source has a wavelength of approximately 254 nm and the
reference light source has a dominant wavelength selected to have
no or little absorption by the sample. 17. In example 16, a method
includes generating a UV sample beam via a UV light source having a
central axis of light extending toward a still or flowing fluid
sample along a central axis of a test cell, wherein the central
axis is substantially orthogonal to a direction of fluid flow,
generating a reference beam via a reference light source having a
central axis of light extending along the central axis of the test
cell, detecting via a first detector, a first portion of the UV
sample beam and reference beam that traverse the test cell, and
detecting via a second detector, a second portion of the UV sample
beam and reference beam directly from the UV light source and
reference light source, wherein the first and second portions of
the UV sample beam and reference beam are substantially parallel
from their sources to the first and second detectors. 18. The
method of example 17 and further comprising calculating a UV
absorption of the fluid sample based on the detecting by the first
and second detectors. 19. The method of any of examples 17-18
wherein generating the UV sample beam and the reference beam
comprises temporally spacing the respective beams such that each
beam is detected separately. 20. The method of any of examples
17-19 wherein the UV sample beam is generated at a wavelength of
approximately 254 nm and the reference beam is generated with a
dominant wavelength selected to have no or little absorption by the
sample.
Although a few embodiments have been described in detail above,
other modifications are possible. For example, the logic flows
depicted in the figures do not require the particular order shown,
or sequential order, to achieve desirable results. Other steps may
be provided, or steps may be eliminated, from the described flows,
and other components may be added to, or removed from, the
described systems. Other embodiments may be within the scope of the
following claims.
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